JPH08187951A - Copper salt for laser marking on thermoplastic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic resin compsn. for laser marking and to produce a product having a laser mark applied thereto. SOLUTION: A copper salt such as copper phosphate, copper sulfate, basic cupric phosphate or copper thiocyanate is contained. This copper salt is added to a thermoplastic resin compsn. in an amt. of about 0.1-5 pts.wt. and pref. has a particle size smaller than 10 μm. A laser mark can be applied so as to impart a region capable of being clearly confirmed or separately discriminated by the naked eye, pref., total color difference different from a base material at least by a delta E value of 10-20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser-markable thermoplastic resin composition, a method for producing them and a method for producing a laser-marked product.

[0002]

BACKGROUND OF THE INVENTION It is known to produce polymeric substances which are capable of inscribing letters, symbols and the like by means of laser light by mixing fillers which change color under the influence of energy irradiation. If it is desired to keep the price of the filler low, only a portion of the amount of filler is mixed with the polymer base (German Patent DE-OS 2,9).
36,926). In particular, the natural, high-contrast, bright-colored inscription of the plastic on a black background is used as a filler in an amount of 0.08 to 0.1.
It can be formed on a plastic surface by laser irradiation after blending 25% of carbon black or graphite. The whiteness of these letters, symbols, etc. can be improved by a fluorescent whitening agent added to the pigment and not destroyed by laser light (German Patent 3,043).
No. 4,722).

Molded products made of a thermoplastic resin containing a polymer having an aromatic structure, which show a very good black color by irradiation with laser light, even without using a discolorable additive, are also known. Is. However,
Since different grades of thermoplastics show very different reactivities, considerable adjustments have to be made regarding process parameters and possibly further material modification. Furthermore, it is also important to have a color which is optimally tuned for the laser light and whose light stability is within the normal range for the product grade. In the case of large molded products, there are processing restrictions related to the thermoplastic grade (Kunststoffe, 78 (198).
8), No. 8, pp. 688-691).

Materials which can be well inscribed by a laser and have good thermal stability and resistance to stress cracking are obtained by mixing 10 to 50% of aromatic polyester with polycarbonate (European patent no. 0,249,082 specification). Finally, laser-based methods of inscribing high molecular weight organic materials, which can achieve good inscribing performance by the incorporation of additives, are known (EP 0,190,997).
See the specification). In particular, commercially available pigments and / or
Alternatively, polymer-soluble dyes are used as coloring additives. Proper contrast inscription on the surface of the material tuned by these additives can preferably be achieved with a Nd-YAG laser with a frequency doubled (wavelength 532 nm after frequency doubled). .

Thus, according to the prior art, polymer compositions are compounded with additives which discolor by selecting a grade of thermoplastic having good laser inscribe performance or under the action of laser irradiation. Can be tailored such that the composition can be inscribed with laser light either by However, in many cases, the amount of color contrast achieved by known methods is not as high as desired. Therefore, there is a constant need for additives that can cause significant discoloration in polymeric materials that incorporate them. further,
It is highly desirable that these additives do not deleteriously affect the beneficial physical properties of the polymer.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to at least one thermoplastic resin composition suitable for laser marking and at least one copper salt selected from the group consisting of copper phosphate, copper sulfate, basic cupric phosphate and copper thiocyanate. The present invention provides a laser-markable thermoplastic resin composition containing: The copper salt is used in an amount sufficient to allow a laser-markable thermoplastic resin composition to absorb laser light outside the visible spectrum. Thus, the portions of the polymer composition that are exposed to the laser light have a color that is clearly visible and separately distinguishable as compared to the base polymer composition.

[0007]

DETAILED DESCRIPTION OF THE INVENTION Most plastic resins can be effectively laser marked by including a copper salt according to the present invention. For example, the present invention has such a high processing temperature that it has a basic color that allows effective laser marking of plastic resins and is not significantly degraded by the copper salt or that the copper salt is degraded during the processing of the resin. Almost any plastic resin that is not needed can be used. According to these criteria, and depending on the particular processing parameters, the plastic material may include either synthetic or modified natural substances, such as cellulose derivatives and plastics obtained by polymerization, polycondensation and polyaddition. At least the following plastic resins, their blends, copolymers and composites may be suitable for laser marking: polyolefins, polycarbonates, polyesters, rubber-modified monovinylidene aromatic resins, polyetherimides, polyamides, polyester carbonates. , Polyphenylene sulfide, polyamideimide, polyesteramide, polyetherester, polyetherimide ester, polyarylate, polymethylpentene, polysulfone, polyethersulfone, polystyrene, rubber modified impact-resistant polystyrene, acetyl, styrene-maleic anhydride Polymer, acrylonitrile-styrene-acrylate copolymer, polyphenylene ether, polyether ketone,
Chlorinated polymers, fluorinated polymers and liquid crystal polymers.

Thermoplastics are the most preferred plastic resins, and polyesters, polycarbonates and rubber-modified monovinylidene aromatic resins and their blends, according to the invention, given the light base color and relatively mild processing conditions. It is particularly suitable for marking. As a result of extensive research, the present inventors have discovered that there are several copper salts with unexpectedly excellent suitability for laser marking of plastic resins. In particular,
These copper salts include cupric phosphate, copper sulfate, basic cupric phosphate (cupric hydroxyphosphate) and cuprous thiocyanate. The inventors have also discovered that many copper salts are unsuitable for laser marking plastic resins. For example, copper salts such as copper acetate, copper naphthenate and copper acetylacetonate were considered unsuitable for laser marking because of their high volatility and the like. Similarly, other copper salts such as copper iodide, copper sulfide and copper oxide are also laser marked because they are black and / or they do not provide sufficient color contrast after exposure to laser light. It was found to be unsuitable for use.

In addition to the copper salt of the present invention, it may be advantageous to add another colorant or mixture of colorants to the plastic resin. However, the colorant or the mixture of colorants can be added only in a concentration that does not impair the laser mark formed in the practice of the present invention. The concentration is typically in the range of about 0.01 to about 5% by weight, depending on the plastic resin.

Suitable additional colorants are inorganic or organic pigments as well as polymer-soluble dyes. Examples of inorganic pigments are white pigments such as titanium dioxide (anatase, rutile), zinc oxide, antimony oxide, zinc sulfide, lithopone, basic lead carbonate, basic lead sulfate or basic lead silicate, and also iron oxide, Nickel antimony titanate, chromium antimony titanate, manganese blue, manganese violet, cobalt blue, cobalt chrome blue, cobalt nickel gray or ultramarine blue, Berlin blue,
Zirconium silicate such as lead chromate, lead sulfochromate, molybdate orange, molybdate red, cadmium sulfide, antimony trisulfide, zirconium vanadium blue and zirconium praseodymium yellow,
And low-concentration color pigments such as carbon black or graphite, and also plate-lit aluminum pigments or mixed phase pigments, for example plate-lit iron oxide with addition of Al2 O3 and / or Mn2 O3, and basic lead carbonate. , Bismuth oxychloride, bismuth oxychloride on a carrier and other pigments including pearlescent pigments such as mica pigments especially coated with titanium dioxide. The last-mentioned pigments further include iron oxide, cobalt oxide,
Other colored metal oxides such as manganese oxide or chromium oxide may be included.

Examples of organic pigments are azo, azomethine, methine, anthraquinone, indanthrone, pyranthrone,
Flavantron, benzanthrone, phthalocyanine,
Perinone, perylene, dioxazine, thioindigo, isoindoline, isoindolinone, quinacridone, pyrrolopyrrole or quinophthalone pigments, and also metal complexes of azo, azomethine or methine dyes or metal salts of azo compounds, as well as platerit type organic pigments. Include.

Examples of suitable polymer-soluble dyes are anthraquinone-based disperse dyes such as hydroxyanthraquinone,
Disperse dyes of aminoanthraquinone, alkylaminoanthraquinone, hydroxyaminoanthraquinone or phenylmercaptoanthraquinone, and metal complexes of azo dyes, especially 1: 2 chromium or cobalt complexes of monoazo dyes, and coumarin, naphthalimide, pyrazoline,
It is a fluorescent dye such as an acridine, xanthene, thioxanthene, oxazine, thiazine or benzthiazole fluorescent dye.

In the practice of the present invention, these inorganic or organic pigments or polymer-soluble dyes can be used alone or as a mixture, conveniently with or without the use of pigment additives. Suitable pigment additives are typically fatty acids having at least 12 carbon atoms,
For example stearic acid or behenic acid and their amides, salts or esters, such as magnesium stearate, zinc stearate, aluminum stearate or magnesium behenate, and also tri (C1 -C4).
Quaternary ammonium compounds such as alkylbenzyl ammonium salts, waxes such as polyethylene wax, abietic acid, rosin soaps, resin acids such as hydrogenated or dimerized rosins, C12-C18 paraffin disulfonic acid or alkylphenols, registered trademark TCD. An alcohol such as alcohol M or vicinal aliphatic 1,2-diol.

The production of plastics resins is carried out in a manner known per se by means of extruders, roll mills, mixers or mills of the necessary coloring constituents (molybdenum disulfide and optionally additional coloring agents), which can be in the form of masterbatches, for example. It is carried out by compounding into a base using a machine. The resulting resin is then formed into the desired final form by methods known per se, such as calendering, molding, extrusion, coating, casting, or injection molding. It is often desirable to incorporate a plasticizer into the organic material prior to processing to produce a non-brittle compact or to reduce the brittleness of the compact. Examples of suitable plasticizers are phosphoric acid esters, phthalic acid esters or sebacic acid esters. The plasticizer can be added before or after the coloring component is added to the polymer.

Depending on the end use, other modifiers such as kaolin, mica, feldspar, wollastonite, aluminum silicate,
Fillers such as barium sulphate, calcium sulphate, chalk, calcite and dolomite, as well as those conventionally used in the processing of light stabilizers, antioxidants, flame retardants, heat stabilizers, glass fibers or plastics and Processing aids known to those skilled in the art can be added to the plastic resin.

The thermoplastic resin composition may further contain other additives well known in the art. For example, the resin composition may contain a surface lubricant, an antioxidant, a flame retardant, and the like. If desired, UV stabilizers, fluidization aids, metal additives for shielding electromagnetic radiation such as nickel-coated graphite fibers, antistatic agents, coupling agents such as aminosilanes, etc. may also be added.

A high energy pulsed laser source is used for marking plastic resins in accordance with the practice of the invention. The procedure applies irradiation energy to match the shape of the marking to be applied, conveniently at a steep angle to the surface of the material to be marked, and the irradiation energy is applied to the marking. It consists of concentrating so that a visually recognizable and separately distinguishable marking is formed in the area of impact without appreciable damage to the surface of the marked material.

Examples of such energy sources are solid-state pulsed lasers such as ruby lasers or frequency doubled Nd: YAG lasers, pulsed lasers with boosters such as pulsed dye lasers or Raman shifters, and CWs with frequency multipliers, for example. Nd: YAG
Continuous wave lasers with laser-based pulse modulators (Q-switches, mode rockers), or CW ion lasers (Ar, Kr), as well as pulsed metal vapor lasers, such as copper vapor lasers or gold vapor lasers, or frequency doubling High-capacity pulsed semiconductor lasers, which emit visible light upon activation, and pulsed gas lasers such as excimer lasers and nitrogen lasers.

Depending on the laser system used, pulse capacities up to a few Joules / cm2, intensities up to 1012 W / cp2, pulse durations from 10-15 seconds to 10-6 seconds and frequencies up to 10 9 Hz are possible. is there. Advantageously, pulse capacities in the microjoule to kilojoule range, intensities in the kilowatt / cm @ 2 to 100 megawatt / cm @ 2 range, pulse durations in the microsecond to picosecond range and frequencies in the range of a few hertz to 50 kilohertz. Can be used.

Preferred lasers are pulsed or pulse-modulated frequency-doubled Nd: YAG lasers or metal vapor lasers such as gold or especially copper vapor lasers as well as excimer lasers. The following table is a list of a number of commercially available lasers that may be suitably used in the practice of this invention.

[0021]table Main wavelength (secondary By model / typical examples Examples of commercially available models Wavelength) [nm] Solid state pulse laser Ruby Laser Laser Metrics (938R6R4L-4) 694 (347) Nd: YAG Laser Quanta Ray (DCR2A) 1064 (532,355,266) Alexandrite Apollo (7562) 730-780 LaserPulse with booster laser Raman Shifter Quanta Ray (RS-1) UV-IR Dye Laser Lambda Physic FL2002 About 300-1000CW with pulse modulator laser Nd: YAG Lasermetrics 532 (Q-Switch, 2ω) (9560QTG) Argon (Mode Lock) Spectra Physics SP2030 514.5,488Pulse metal vapor laser Cu Vapor Laser Plasma-Kinetics 751 510,578 Au Vapor Laser Plasma-Kinetics 628 Mn Vapor Laser Oxford 534,1290 Pb Vapor Laser Laser CU25 723 Semiconductor Diode Laser M / ACOM Model LD65 About 905, (402) Semiconductor Diode Laser STANTEL Model LF100 About 905, (402) arrayPulse gas laser Excimer XeCl Lambda Physic 308 XeF and EMG-103 351 N₂ 337 Parameters such as pulse capacity and pulse duration
The laser allows easy adjustment of the laser
The best suitability for the requirements of the material to be
Can achieve a response.

The best wavelength to be selected for irradiation is that which is most strongly absorbed by the radiation-sensitive copper salt and optionally added colorant, while the plastic material to be marked is mostly absorbed. Not a wavelength. Laser light having a wavelength in the IR range is preferably used. By "near infrared region" is meant a region in the range of about 0.78 μm to about 2 μm.

In practicing the present invention, three different methods are commonly used for laser marking, usually the mask method, the linear marking method and the dot matrix method. In these last two methods (autofocusing), the laser is preferably combined with a laser marking system, whereby the plastic material is optionally, for example computer programmed,
It can be marked by the method of using the numerical display, the character display and the special symbol display.

The choice of laser system in terms of capacity and frequency is basically related to the marking method used. For example, high capacities and low frequencies of solid state pulsed lasers and excimer lasers are preferred for mask exposure. Moderate to low volumes and fast frequencies of pulsed metal vapor lasers or continuous wave lasers with pulsed modulators are preferred for the formation of markings requiring automatic focusing. Beam deflection can be performed, for example, acousto-optically, holographically, using a galvo-mirror or a polygon scanner. Self-focusing allows the marking to be very flexible as it can be electronically formed.

[0025]

[Description of Examples]

Example 1 This example demonstrates several copper salts found to provide effective laser marking of thermoplastics. These copper compounds are specially developed grades for use in keycaps, registered by General Electric Company under the trademark "Valox" 3
Evaluated for use in a thermoplastic polyester sold as 25C.

Nd / operating at a wavelength of 1064 nm
These disks were marked using a YAG laser. Aside from the composition of the materials, the laser setting was relatively important. The optimum settings were related to scan speed, lamp current, Q-switch and mode blender. The lamp current and Q-switch were varied as a function of scan speed to determine the optimum setting. The former results showed that the mode blender should have a 1.0 mm diaphragm. Small squares (1 x 1 cm) were marked using the setting that gives the best contrast. This area allowed the measurement of the color difference between the background and the marked area (Cielab (Cie).
Lab) method, DIN test method 6174, source D65).
A Delta E value of 20 is generally considered sufficient. A. Copper sulfate 1 2 3 4 5 6 Barox 325C 100 100 100 100 100 100 Titanium dioxide 2.8 4.3 4.3 4.3 4.3 4.3 Carbon black 0.015 0.015 0.015 0.015 0.015 0.015 Copper sulfate (solid) 1.5 Copper sulfate (solution) 0.05 0.1 0.5 1.5 Delta E 12.5 16.7 21.3 21.4 19.1 14.8 B. Copper Phosphate 1 7 8 9 10 11 Barox 325C 100 100 100 100 100 100 Titanium Dioxide 2.8 4.3 4.3 4.3 4.3 4.3 Carbon Black 0.015 0.015 0.015 0.015 0.015 0.015 Copper Phosphate (PS = 30 μm) 3 Copper Phosphate (PS = 15 μm) 3 1.5 Copper phosphate (PS = 6 μm) 3 1.5 Delta E 12.5 17.7 23.6 20.6 25.4 24.1 PS = particle size, 90% of the particles are smaller than the given value. C. Copper thiocyanate 1 12 13 14 15 Barox 325C 100 100 100 100 100 Titanium dioxide 2.8 4.3 4.3 4.3 4.3 Carbon black 0.015 0.015 0.015 0.015 0.015 Copper thiocyanate 0.75 1.0 1.5 3 (PS = 0.4μm) Delta E 12.5 20 21.9 23.3 19.9 D ． Copper thiocyanate 16 17 18 Barox 325C 100 100 100 Titanium dioxide 2.8 4.3 4.3 Copper thiocyanate (PS = 0.4 μm) 1.5 3 Delta E 25.5 36.6 38.5 Addition of 3 pbw copper thiocyanate to a Barox 325C containing composition is a CO 2 -laser. Sensitivity to was significantly improved. In the absence of the laser-sensitive additive, the plastic material is simply ablated, but in the presence of this additive, a grey-brown sign appears after irradiation.

Example 2 A direct comparison was made between cupric phosphate, cuprous thiocyanate and basic cupric phosphate as possible contrast enhancing additives. The following additives were evaluated in a polyester resin sold under the registered trademark Barox 325C manufactured by General Electric.

Additives used: Basic cupric phosphate; Aldrich 34,440-0,
97% cupric phosphate; Scmidt B.I. V. M
13-32 Cuprous thiocyanate; HCA Holland Colors (Hollan
d Colors) All laser experiments were performed using a Nd: YAG 1064 nm laser [Model LBI6000; Supplier:
Carl Bassell Laser Technique (Carl B
aasel lasertechnik) GmbH; focal length: 160 mm; working distance: 180 mm].

The laser setting was optimally selected by the same method as in Example 1. Measure the contrast and C
Defined as Delta E (marked area vs. background) according to the ieLab method (DIN 6174, source D65). A. Basic cupric phosphate Cu ₂ (OH) PO ₄ (pbw) 0 0.5 1 1.5 2 3 (composition pbw) Barox 325C 100 100 100 100 100 100 titanium dioxide 4.3 4.3 4.3 4.3 4.3 4.3 carbon black 0.015 0.015 0.015 0.015 0.015 0.015 (laser setting) Mode blender (mm) 1.0 1.0 1.0 1.0 1.0 1.0 Lamp current (ampere) 18 16 14 14 14 14 Q-switch (hertz) 2000 2000 2000 2000 2000 2000 Speed (mm / sec) 200 175 225 225 225 225 Wobble (mm) 0 0 0 0 0 0 Delta E 16.3 15.8 18.9 20.4 23.2 21.7 B. Cupric phosphate Cu ₃ (PO ₄ ) ₂ (pbw) 0 0.5 1 1.5 2 3 (composition pbw) Barox 325C 100 100 100 100 100 100 Titanium dioxide 4.3 4.3 4.3 4.3 4.3 4.3 Carbon black 0.015 0.015 0.015 0.015 0.015 0.015 ( Laser setting) Mode blender (mm) 1.0 1.0 1.0 1.0 1.0 1.0 Lamp current (ampere) 16 16 14 14 14 14 Q-switch (hertz) 2000 2000 2000 2000 3000 3000 Speed (mm / sec) 225 200 200 200 225 225 Wobble (mm) 0 0 0 0 0 0 Delta E 16.3 17.2 18.8 20.8 20.7 22.6 C. Cuprous thiocyanate CuSCN (pbw) 0 0.5 1 1.5 (composition pbw) Barox 325C 100 100 100 100 titanium dioxide 4.3 4.3 4.3 4.3 carbon black 0.015 0.015 0.015 0.01 (laser setting) mode blender (mm) 1.0 1.0 1.0 1.0 lamp current (Amperes) 16 16 14 14 Q-Switch (Hertz) 2000 2000 2000 2000 Speed (mm / sec) 225 225 225 225 Wobble (mm) 0 0 0 0 Delta E 16.3 18.8 22.3 24.7 From the above teachings to other inventions It will be apparent to those skilled in the art that modifications and changes can be made. Therefore, it goes without saying that various modifications can be made to the specific embodiment described above within the scope of the invention defined in the claims.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Theodorus Lambertus Hoax Holland, 4613, Aes Bergen op Zoom, Holstersweg, No. 303 (72) Inventor Andre A Volkers Holland, 4353, SK Sheer Roskerk, Gapin Sedleaf, No. 1

Claims (18)

[Claims] 1. The following components: (a) at least one thermoplastic resin composition suitable for laser marking; and (b) a group consisting of copper phosphate, copper sulfate, basic cupric phosphate and copper thiocyanate. At least one copper salt selected from the above, the copper salt being a ratio sufficient to allow a laser-markable thermoplastic resin composition to absorb a laser beam outside the visible spectrum, that is, the laser beam of the composition. It shall be present in such a proportion that the absorbing part has a color which is clearly visible to the naked eye and which can be separately distinguished;
A laser-markable thermoplastic resin composition comprising: 2. The thermoplastic resin composition according to claim 1, wherein the wavelength of the laser light is greater than about 900 nm. 3. The thermoplastic resin composition according to claim 1, wherein the copper salt is copper phosphate or copper thiocyanate. 4. The thermoplastic resin is polycarbonate, polyester, rubber-modified monovinylidene aromatic resin, polyetherimide, polyesteramide, polyamide, polyester carbonate, polyphenylene sulfide,
Polyamideimide, polyetherester, polyetherimide ester, polyarylate, polymethylpentene, polysulfone, polyethersulfone, polystyrene, rubber-modified high-impact polystyrene, acetyl, polyphenylene ether, polyetherketone, chlorinated polymer, fluorine The thermoplastic resin composition according to claim 1, comprising at least one resin selected from a chemical polymer, a liquid crystal polymer, a copolymer of the above, or a blend of the above. 5. The thermoplastic resin is polyester, polycarbonate, polyester carbonate, rubber-modified monovinylidene aromatic resin, polyetherimide, polyesteramide, polyetherester, polyetherimide ester, or a copolymer or blend of the above. The thermoplastic resin composition according to claim 4, which comprises a substance. 6. The thermoplastic resin composition of claim 5 wherein said thermoplastic resin comprises polycarbonate, polyalkylene terephthalate, rubber modified monovinylidene aromatic resin, or a copolymer or blend of the foregoing. 7. The thermoplastic resin composition according to claim 2, wherein the proportion of the copper salt is in the range of about 0.05 to about 10 parts by weight of the thermoplastic resin composition. 8. The thermoplastic resin composition of claim 7, wherein the proportion of said copper salt is in the range of about 0.1 to about 5 parts by weight of the thermoplastic resin composition. 9. The thermoplastic resin composition of claim 1, wherein the proportion of said copper salt is in the range of about 0.5 to about 3 parts by weight of the thermoplastic resin composition. 10. The thermoplastic resin composition of claim 2, wherein the particle size of the copper salt is less than about 10 μm. 11. The thermoplastic resin composition of claim 10, wherein the copper salt has a particle size of less than about 1 μm. 12. The thermoplastic resin composition of claim 2 wherein the total color difference between the base composition and the portion that has absorbed the laser light is at least 10 units as measured by Delta E. 13. The thermoplastic resin composition of claim 12, wherein the total color difference between the base composition and the portion that has absorbed the laser light is at least 15 units as measured by Delta E. 14. The thermoplastic resin composition of claim 13, wherein the total color difference between the base composition and the portion that has absorbed the laser light is at least 20 units as measured by Delta E. 15. The thermoplastic resin composition according to claim 2, wherein the composition further comprises carbon black or titanium dioxide. 16. A laser-markable product containing the thermoplastic resin composition according to claim 1. 17. A method for producing a laser-markable thermoplastic resin composition, which comprises the step of extruding the thermoplastic resin composition according to claim 1. 18. The following steps: (I) The following components: (a) at least one thermoplastic resin composition suitable for laser marking; and (b) copper phosphate, copper sulfate, basic cupric phosphate. And at least one copper salt selected from the group consisting of copper thiocyanate, and the copper salt is a proportion sufficient to allow a laser-markable thermoplastic resin composition to absorb laser light outside the visible spectrum, that is, It shall be present in such a proportion that the laser light absorbing part of the composition has a color which is clearly visible to the naked eye and which is separately distinguishable;
A thermoplastic resin composition comprising: and (II) laser marking the molded article with a laser having a wavelength outside the visible spectrum; Manufacturing method of customized products.